This invention is related to the technology of Chemical Vapor Deposition (CVD) diamond growth. This is a subject of intense interest, not only due to basic research, but mainly to the many possible technological applications. Some of its superior properties make diamond the material of choice for many applications. Some CVD growth techniques have been developed at Instituto Nacional de Pesquisas Esnaciais (INPE) and the present invention is a result of this development.
An object of the invention is fundamented in the growth of thin and free standing CVD diamond films. These diamond films may be directly deposited and/or brazed on pins of stainless steel or any other material, to be used as burrs, mills and files in odontological and related work.
The diamond films may be obtained by the Hot Filament Chemical Vapor Deposition (HFCVD) or any other CVD technique. The HFCVD technique is particularly suitable due to its simplicity and low cost. Therefore we describe the obtainment of thin and free standing films based on the HFCVD technique. To use other growth techniques it is necessary to adapt the growth conditions to the appropriate activation method.
The procedure to obtain burr from thin and freestanding diamond films with poor adherence with the final burr stick is as follows:
a) preparation of substrate pins of a material suitable for diamond growth, molybdenum for example. The diameter and the length of such pins depend on the growth parameters and growth method. The upper end must be prepared to have the final form of the burr tip;
b) deposition of the diamond film on the upper end of the substrate pins prepared in the previous item. The growth conditions in the reactor for the deposition of the freestanding diamond tip must be adjusted in order to obtain the largest grain size. The boring and abrading capabilities depend on the grain size of the burr tip.
c) dissolution of the substrate pins in acid solution to release a freestanding diamond tip;
d) laser trimming of the diamond tip, or any other trimming method, to eliminate its fragile end;
e) brazing of the diamond tip on the final burr stick, made of stainless steel or any other suitable material, to obtain the final burr form. The excess of brazing alloy is removed to free the diamond cutting surface.
If the final burr stick is suitable for diamond growth with good film adherence, the procedure is as follows:
a) preparation of the burr stick in its final form;
b) preparation of the burr stick end surface to assure a good adherence of the diamond film;
c) deposition of a thin or thick diamond film directly on the burr stick end.